Lacquer solvent and thinner



Nov. 30, 1937. F. A. BENT ET AL LACQUER SOLVENT AND THTNNER Filed Aug. 8, 1956 v tion characteristics.

Patented Nov. 30, 1937 UNITED STATES LACQUER SOLVENT. AND THINNERy Franklin A. Bent and Simon N. Wik, Berkeley,

and William Pong, San Francisco, Calif., as-

signors to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application August 8, 1936, Serial No. 94,9191/2 9 Claims.

of solvent mixtures which notonly have a high.

solvent power for cellulose derivatives, especially nitrocellulose, and yet form solutions of low viscosity but also which have a suitable evaporation range and resistance to humidity which insures deposition of lms which are tough, clear and homogeneous. 'I'hese advantages are combined in our novel mixtures with cheapness of starting materials and stability of the compounded product.

We have found that it is neither necessary nor desirable to have eiective amounts of organic esters present in solvent mixtures for cellulose derivatives and that better lacquers and lacquerA thinners may be prepared using a. mixture of ketones having a smooth evaporation curve and one or more alcohols, preferably of similar evapora- By properly proportioning the alcohol content to the amount of mixed ketones used, solvent mixturesl may be prepared which are capable of Amuch higher dilution with the usual diluents, particularly aromatic diluents, than has been considered possible with prior solvents.

In the liquid solvent compositions of our invention the proportions of the ingredients, i. e; ketone mixtures, alcohol or alcohols and diluent or mixed diluents may be `varied quite widely' depending upon the cellulose derivative or derivativesl with which the solvent'is to be used, the use to which the finished product is to be put, the nature of the lvarious components chosen, particularly the gums, resins, plasticizers and like ingredients used in the preparation of lacquers, the evaporation rate desired, the excess tolerance r specified, and like factors.

A wide variety of ketones, alcohols and diluents may be used in the liquid solvent compositions of our invention. As components of the ketone mixturesrwhich are suitable in our products are included both aliphatic,` carbocyclic and aromatic ketones. Typical aliphatic ketones which may be included in the ketone mixture used are, for example, saturated ketones such asz' acetone, methyl-ethyl ketone, methyl-propyl ketone, methylisopropyl ketone, diethyl ketone, ethyl-propyl ketcne, methyl-n-butyl ketone, methyl-secondary butyl ketone, methyl-tertiary butyl ketone, dipropyl ketone, di-isopropyl ketone, propyl-lsopropyl ketone, ethyl-butyl ketone, `methyl-amyl ketone, di-isobutyl ketone, methyl-n-hexyl ketone and higher homologues and unsaturated ketones, such as methyl vinyl ketone, vinyl acetone, allyl acetone, mesityl oxide, propyl-allyl ketone, etc. Cyclic and aromatic ketones such as cyclobuta- 'none, cyclopentanone, cyclohexanone, acetophenone, benzophenone, etc. may also be present in the ketone mixtures used. The ketones are preferably chosen according to their evaporation rates to include fast, medium'and slow evaporating ketones so as to obtain a smooth evaporaticn curve. Three or more aliphatic ketones differing in carbon content by, preferably, not more than.

two carbon atoms per molecule between individual compounds and covering a range of difference of not less than two carbon atoms per molecule provide such suitable evaporating mixtures. Thus, for example, a. mixture of methyl-ethyl ketone, di-ethyl ketone and methyl-butyl ketone or a mixture of methyl-ethyl ketone, mesityl oxide and di-propyl ketone may beused. rIn some cases, however, two ketones may be sufficient to produce the desired evaporating range. .-The alcohol or alcohols used are chosen with respect to the ketone'mixture with which they are to be used so as to produce mixtures in which the sol-W vent balance will be preserved during evaporation. Typical preferred combinations include, for example, methyl alcohol with methyl-ethyl ketone, ethyl alcohol (preferably anhydrous) with methyl-propyl ketone, isopropyl alcohol with diethyl and/or methyl-isobutyl ketones. secondary and/or tertiary butyl alcohol with mesityl oxide and/or methyl-n-butyl ketone, n-butyl and/or secondary amyl alcohols with methyl-n-amyl ketone, methyl-amyl alcohol with cyclohexanone, etc. Thus in general, aliphatic alcohols which have two or three less carbon atoms than the aliphatic ketones with which they are used are preferred, although a singlealcohol or any number of alcoholsV having suitable evaporation characteristics, may be used. f

The diluent or diluent mixture used is similarly chosen to have a rate of evaporation' in the presence of the cellulose derivative with which it is to be applied which is similar to, or preferably faster than, the rate of evaporation ofthe ketone mixture with which it is to be used. Thus with etc.. benzol is suitable, while with methyl-propyl and/or methyl-isobutyl ketones, for example, toluene is more advantageous. Monochlorbenzene, butylene di-chloride and analogous halogenated hydrocarbons are useful in mixtures containing mesityl oxide, methyl-n-butyl ketone, etc. Slower evaporating mixtures containing dipropyl ketone, methyl-n-amyl ketone and the like more preferably containdiluents such as xylene. Diluents of an aliphatic nature may be used in place of the above described aromatic diluents provided they are so chosen that the resulting mixtures will evaporate at the same rates.v Mixed aromatic-aliphatic diluents may also be used. In all cases higher dilution ratios are possible by the use of aromatic diluents than with diluents preponderantly of an aliphatic nature. Since aromatic compounds are less desirable, from an economic standpoint, in the range of dilution ratios in which diluents preponderantly composed of aliphatic compounds may be successfully used, we preferably employ aromatic diluents in such proportions to the solvent mixture, i. e. ketone mixture plus alcohol, as are at least equal to -about the maximum proportions of preponderantly aliphatic diluents of similar evaporation rate which will form a solution of. the cellulose derivative involved of the same concentration.

For the purpose of making our invention more clear it will be described with more particular reference to the accompanying drawing in which the limiting solubility of l second nitrocellulose at a concentration of 8% in systems composed of the three components (1) a typical ketone mixture consisting of methyl-ethyl, methylpropyl and methyl-butyl ketones (2) any aliphatic alcohol and (3) diluent, have been plotted on triangular coordinates. In this drawing all compositions represented by points above curve :1s-y will dissolve at least 8% by weight of nitrocellulose when the diluent contains only aromatic compounds. All compositions above curve z-y will dissolve at least 8% by weight of nitrocellulose When the diluent contains substantially only open-chain compounds. Compositions below their respective curves will dissolve less than 8% of nitrocellulose when the corresponding diluents are used. i

It is obviously not desirable in preparing 8% nitrocellulose solutions to use the exact compositions indicated by curves .i2- y with aromatic diluents or a-y with aliphatic diluents since these curves represent maximum dilution ratios, de-

fined as the ratio of the weight of diluent to the weight of solvent (ketone mixture and alcohol or alcohols) at which the mixture just ceases to be a solvent for nitrocellulose at 8% final concentration. Compositions corresponding to points above the respective curves are therefore necessary. The distance above the limiting curve in question which it will be desirable to choose will depend upon the excess tolerance required in the solvent mixture, that is the amount of additional solvent which may be added to one pound of mixture before causing precipitation of nitrocellulose. This may conveniently be calculated according to the equation B X excess tolei` ance where B=the dilution ration and =weight of diluent which is added to the solvent to give the required excess tolerance. Curves :r1- y and :r2-y show the proportions of aromatic diluent, ketone mixture and alcohol or alcohols o! two or more carbon atoms which will form 8%. 'nlu- Percent Aromatic diluent 83 Ketone mixture 12 Alcohol or alcohols 5 That the composition of suchmixtures is the same for different systems, i. e., different ketones with different aliphatic alcohols and aromatic hydrocarbons have the same relative composition at the maximum dilution ratio, is shown by the following table:

Compositions of ternary mixtures containing maximum amount of toluene Percent ketone Percent alcohol g 12% methyl ethyl ketone 5% ethyl alcohol 83 12% methyl ethyl ketone 5% isopropyl alcohol 83 12% methyl ethyl ketone 5% n-butyl alcohol 83 5% s-butyl alcohol 83 5% t-butyl alcohol.. 83

5 methyl alcohol 82 5% ethyl alcohol 83 12% methyl propyl ketone. 5% isopropyl alcohol-.. 83 12% methyl propyl ketone 5% n-butyl alcohol 83 12% methyl propyl ketone 5% s-butyl alcoho1. 83 '12% methyl propyl ketone 5% t-hutyl alcohol 83 13% methyl propyl ketone 5% methyl alcohol 82 In general, compositions corresponding to points above the maximum dilution curve (curve the maximum dilution curve for open-chain hydrocarbons are used only when diluents which are predominantly of that type are resorted to. Hydro-aromatic compounds, such as cyclohexane, and mixtures of aromatic and open-chain compounds and other suitable diluents which have higher dilution ratios than products containing substantially only open-chain compounds may be used in the same proportions as such open-chain compounds if desired but preferably are employed in larger amounts.'

Except in special cases, as where lacquer concentrates which are to be diluted before applications are prepared, we prefer to use compositions containing less than 50% alcohol as large amounts of alcohol simply act in part as diluents.- Particularly useful are those compositions containing an alcohol-ketone-mixture ratio of about 0.25 to about 0.75 to 1 or more preferably about 0.25 to about 0.55 to 1, by Weight as in these ranges the, maximum dilution at each concentration of nitrocellulose may be had. In general mixtures containing at least about 25% diluent, whatever its nature, are preferred.

Suitable compositions for lacquer formulation may contain, for example, from 3 to 55% of a mixture of ketones, from 1 to 50% of alcohol and from 44 to 83 '7.2 of aromatic hydrocarbon. The ketone pcrtion of the mixture is most suitably made up of at least three different ketones coverlng a range of evaporation of fast, medium and slow evaporating ketones in the proportion of about 20 to 40% by weight of the faster evaporat- .ng ketone, about 25 to 50% of the medium evaporating ketone and about 20 to 40% of the slower evaporating ketone. In some instances two ketones may be suicient in which case preferable proportions are about 50 to r10% medium or slow evaporating ketone and the remainder faster evaporating ketone. Where the composition is to have a medium evaporation rate, the ketone mixture may suitably be made up, for example, of

lmethyl-isobutyl ketone 20 to 40%, methyl-nbutyl ketone 25-to 50% and methyl-secondary amyl ketone 20 to 40%. With such a ketone mixture the alcohol content of the solvent composition may advantageously be made up, for example, of isopropyl alcohol 20 to 40%, secondary butyl alcohol 25 to 50% and isobutyl alcohol 20 to weight .may be used.

Wherev diluents preponderantly made up ofopen-chain compounds are to beused, the proportions of ingredients may, for example, be of the order of 14 to'74% of ketone mixture, from about 1 to about 50% alcohol content and from about 25 to about 45% of diluent. The nature and proportions of the individual ketones and alcohols may be the same as those described above as suitable with aromatic diluents or may differ therefrom in accordance with the use to which the mixture is to be put.

Examples of typical mixtures which are suitable as nitrocellulose solvents are as follows:

Example I Ingredients Percent (by weight) Methyl ethyl ketone 4.0 Methyl propyl ketone 4.0 Methyl butyl ketone 5.0 Ethyl alcohol 3.0 Isopropyl alcohol 3.0 Secondary butyl alcohol 3.0 Toluene 52.0 `Xylene 26.0

Example II '0 Ingredients Percent (by weight Methyl ethyl ketone 8.6 Methyl .propyl ketone 9.2 Secondary butyl alcohol 15.1 Methyl amyl ketone 9.3 Petroleum hydrocarbon 57.8

While we have described our invention with more particular reference to the preparation of mixtures especially suitable for production of the standard 8% solutions of 1/2 seco'nd nitrocellulose this hasbeen for the purpose of illustration only and it will be understood that we are not to be limited thereto as our novel compositions are not only advantageous with nitrocellulose of other viscosities, particularly 6 second nitrocellulose forv other esters such as cellulose xanthate, acetate, propicnate, butyrate, etc. (whether mixed esters or not) and ethers, for example, the methyl, ethyl,

propyl, butyl and/or amyl ethers of cellulose (whether iso or straight chain or primary, secondary or tertiary in character) as Well as their corresponding ether-esters. It will of course be recognized that these various derivatives will in each case have different solubility limits in the solvent mixtures of our invention which will require corresponding changes in the proportions of the preferred mixtures but in all cases the most advantageous solvent mixture will be one containing a plurality of ketones, at least one alcohol and a diluent in such proportions that Where the diluent is of an aromatic character the diluent content is at least equal to the maximum proportions of open-chain diluent which would form an otherwise similar solution.

Our novel products have many advantages over prior lacquer solvents and thinners. As a result of the substantial elimination of organic esters they are stable and do not liberate corrosive organic acid by hydrolysis during storage and may safely be kept in metallic containers. The high solvent power of the ketones results in cellulose derivative solutions of low viscosity making it possible to spray higher concentrations and/or more viscous grades of cellulose derivatives than has heretofore been practical. By proper proportioning of the components larger amounts of diluent may be added and/or cheaper open-chain hydrocarbon compounds may be used. Furthermore, by the use of diluents and alcohols which have evaporation rates in the presence of the cellulose derivative involved substantially corresponding to the rates of evaporation of the ketone mixture used, the absorption of water duringthe whole drying time of the lacquer film resulting in smo'oth illms of high resistance to humidity, i. e. substantially Zero blush.

' consisting of from 3% to 74% by weight of a mixture of ketones having a smooth evaporation c urve, from 1% to 50% by weight of an alcohol, and from 25% to 83% by weight of a conventional liquid hydrocarbon diluent material, the alcoholcontent and the hydrocarbon-content of the mixture having evaporation rates similar to the evaporation rate of the ketone mixture, said solvent mixture having ketone mixture and hydrocarbon '.'diluent ranges of 3% to 55% by weight and 44% to 83% by Weight, respectively, when the diluent is an aromatic hydrocarbon, and ketone' mixture and hydrocarbon-diluent ranges of 14% to 74% by Weight and 25% to 45% by weight. respectively, when the diluent is an aliphatic hydrocarbon, whereby the solvent mixture isevaporative without any substantial variation in the ketone to alcohol ratio therein.

2. A liquid .solvent mixture suitable for the manufacture of lacquers and lacquer thinners which has a high solvent power for cellulose ethers, esters and ether-esters and forms theref rwith solutionsiof high concentration and low vis-` cosity characterized by'having a smooth evaporation curve over a wide range and high resistanoe'fto humidity during drying resultinginthe deposition of lms of the cellulose yderivative which are clear, tough, homogeneous' and subf stantially devoid of blush, said solvent. mixturek consisting ofy fror'nf3% to r55% yby yweight'oi a mixture of :ketones having a smooth evaporation curve, 1% lto 50%- bylweightlof-atleast'one alcohol,r andr from y44%y to,83f% yby weight yof an aromatic hydrocarbon diluent the alcohol-content rand the hydrocarbon-content of the mixture'having evaporation'rates similar to theevaporation e rate of the ketone mixture whereby the solvent mixture is evaporative without. any substantial variation of the ketone 'to alcohol therein.y

3. A liquid *solvent` mixture suitable for-'the cosity characterized by*r having a smooth yevap-tioration lcurve over a wide range and' high resistanceto humidityiduring drying resulting in the deposition vof 'lm's' of 'the f cellulose derivative `i which lare clear, tough, homogeneous andfsubfan aromatichydrocarbon diluent, the alcoholf ethers, esters and ether-estersandforms there- "with Asolutions .of high .concentration andlow f manufacture of lacquers andy lacquer ,thinners' f which is capable of dissolving a'suncient amount f of one-half second nitrocellulose to form at least stantially :devoid of blushs said solvent mixture consisting of from 12 %v to 25% by weight of a mixture of aliphatic ketones` having a' smooth f evaporation curve, 5% to .10%'by weight of a mixture of aliphatic alcohols,and 66% to v83% by weight of content andthe hydrocarbon-content of the mixture 'having' evaporationr rates f similarvr to f the' revap'oration'rate of the ketone mixture whereby the' solventl mixture is` evaporative without i any ratio: therein.

y4. A liquid solvent mixture. suitable for the an 8% by weight solution thereof which has a low viscosity and is characterized by having a smooth evaporation curve over a relatively long drying period and high resistance to humidity during drying resulting in deposition of nitrocellulose lms which are clear, tough, homogeneous and substantially devoid of blush consisting or from 12% to 25% by weight of a mixture of aliphatic ketones having a smooth evaporation curve, 5% to 10% by weight of a mixture of aliphatic alcohols, and 66% to 83% by weight of an aromatic hydrocarbon diluent, the alcohol-content and the hydrocarbon-content of the mixture having evaporation rates similar to the evaporation rate of the ketone mixture whereby the solvent mixture is evaporative without any substantial variation in the ketone to alcohol ratio therein.

5. A liquid solvent mixture suitable,v for the manufacture of lacquers and lacquer thinners which has a high solvent power for cellulose ethers, esters and ether-esters and forms therewith solutions of high concentration and low viscosity characterized by having a smooth evaporation curve over a wide range and high resistance to humidity during drying resulting in the deposition of films of the cellulose derivative which are clear, tough, homogeneous and substantially devoid of blush, said solvent mixture kmatieaiment-the1alcolicheeinem; and the h5, rdrocarbon,-content of the. -mixture having evapyorationrates similarv to the evaporation rate of the ketone mixture wherebyr the solvent mixture isevaporative withoutany substantial variation in the ketone to alcohol ratio therein.

e. A liquid solvent. mixturey suitable for the manufacture zoi lacquers and lacquer thinners oration-'curve over a wide range and high resist-y ance to. humidity during drying `resulting in the deposition of lms rof ther cellulose derivative consisting of 13%y byy weight"y of a mixturer of substantially equal weight proportions of three different aliphatic ketones containing four, ilve and sixvcarbon atoms, respectively, 9%- by weight -oi a-mixture of substantially equal weight proportions ofthree different aliphatic alcohols con-.

taining two,vthree andv fourv carbon atoms, .re-

manufacture of. lacquers and lacquer thinners which hasr a :high vsolvent power y for cellulose .3oy -7. .A liquid solvent mixture suitabler for ther f viscosity characterized by having a smooth evapl oration curve over a wide range and high resistance to humidity during drying .resulting in the deposition vofy films ofthe cellulose derivativel -which are .clear,'tough. homogeneous and sub-y stantially devoid of blush, said solvent `mixture 'consisting' of 27%r byr weight-r of a` mixture lof ysubstantially equal proportions of three differenty f f aliphatic ketones containing four, five and seven carbon atoms, respectively, 15% by weight of an aliphatic alcohol containing four carbon atoms, and 58% by weight of a petroleum hydrocarbon fraction having an evaporation rate similar to the evaporation rate of the ketone mixtureV and the alcohol, whereby the solvent mixture is evaporative without any substantial variation in theY ketone to alcohol ratio therein.

8. A liquid solvent mixture suitable for the manufacture of lacquers and lacquer thinners phatic ketones containing substantially equal weight proportions of methyl ethyl ketone, methyl propyl ketone and methyl butyl ketone, 9% by weight of a mixture of aliphatic alcohols containing substantially equal weight proportions of ethyl alcohol, isopropyl alcohol and secondary butyl alcohol, 52% by weight of toluene and 26% by weight of xylene, said solvent mixture being evaporative without substantialA change in the ketone to alcohol ratio therein.

9. A liquid lacquer composition of low viscosity l5` rwhichare clear, tough, homogeneous and subv .f 1 stantially devoid of blush, said solvent mixture aimee@ which is suitable for spraying and characterized by having a smooth evaporation curve over a wie range and a high resistance'to humidity during drying resulting in the deposition of films which are clear, tough, homogeneous and substantially -devoid of blush, saidcomposition containing 8% by weight of one-half second nitrocellulose dissolved in a. liquid solvent consisting of 12% by weight of a mixture of aliphatic ketones liaving a smooth evaporation curve, 5% by weight) of at least one aliphatic alcoholfand 83% by weight oi an aromatic hydrocarbon diluent, the alcohol=content and the hydrocarboncontent of the mixture having evaporation rates similar to the evaporation rate of the ketone mixture whereby the lcomposition is evaporative without substantial change in the ketone to alcoholl ratio therein. 4

FRANKLIN A. BENT.

SIMON N. Wm. 

